Overload indicator



1949- E. s. BUNDY 2,479,468

OVERLOAD INDICATOR Filed Jan. 17, 1947 f I m INVENTOR. EDWlN Smeon BUNDYATTORNEY Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE OVERLOADINDICATOR Edwin Simeon Bundy, Hamburg. N. Y., assignor to Line MaterialCompany, Milwaukee, Wis., a

corporation of Delaware Application January 17, 1947 Serial No. 722,516

transformers are mounted on poles and these visual means are not readilynoticeable to persons on the ground unless they are specifically lookingfor the indication.

This invention has for its primary object the" provision of an audibleoverload indicator for distribution transformers which will give aclearly audible signal designed to attract the attention not only of alineman who may or may not be looking for the indication, but also willattract the attention of any person in the vicinity and of the customerswho will hear the audible indications in their homes as the device is soarranged and associated with the transformer and its casin that a partof the casing, such as the cover, acts as a sounding board. It isexpected that the customers or other persons in the vicinity, in turn,will'call up the power company and notify it.

Further objects are to provide a very simple and easily produced devicewhich may be installed in the casing of a transformer with the utmostease and without requiring any changes in the transformer. The device isheld in place by the cover of the transformer, and will coact with thecasing of the transformer to give a clearly audible sound when thetransformer is overloaded.

Embodiments of the invention are shown in the accompanying drawings, inwhich:

Figure 1 is a fragmentary view partly in section showing the deviceinstalled within the casing of a distribution transformer.

-Figure 2 is a fragmentary diagrammatic view of the electrical circuitsemployed.

Figure 3 is a viewof a modified form of a thermally responsive device.

Figure 4 is a view of a further form of a thermally responsive device.

Referring to the drawings, it will be seen that a distributiontransformer has been indicated by the reference character I. Thistransformer is housed within a casing whose body portion is indicated bythe reference character 2 and whose cover is indicated by the referencecharacter 3. The cover is provided with a gasket 4 and is clamped downon to the body portion 2 in any well known manner, not shown. Thecasing'2 is partially filled with oil, for instance to the levelindicated by the dotted line 5. The overload indicating device comprisesa hanger 6 which is of bell crank shape and has one arm '1 projectingdownwardly and bearing against the inner side of 3 Claims. (Cl. 177-311)the body portion 2 of the casing. The other portion of the hangercarries the audible indicating device indicated generally by thereference character 8. This device may comprise an electromagnet whoseenergizing winding is indicated by the reference character 9. Thisenergizing windin is wound around a bolt III which forms the core of theelectromagnet and terminates in a downwardly projecting head II. A yokel2 of magnetic material is also held in place by means of the bolt Ill.The bolt I passes through the hanger 6 and thus secures theelectromagnet firmly to the hanger. A vibrating armature is indicated bythe reference character l3 and is formed of resilient magnetic material.One end is securely fastened to the hanger 6 and the other end is inspaced relation to the head ll of the core or bolt Ill and the yoke l2,the yoke I2 it being noted having its lower end spaced from the head llof the core.

It is clear that when the electromagnet is energized with alternatingcurrent that the armature l3 willvibrate rapidly and will strike amultitude of blows on the head I l of the core or bolt Ill. Theresiliency, length and weight of the armature l3 are so chosen that thearmature is resonant to the alternating current frequency of the supplycircuit.

The hanger B is somewhat resilient and is arranged to force the bolt orcore in into firm engagement with the cover 3 so that the impact of theblows is transmitted to the cover 3 and the cover, therefore, acts as asounding board. A convenient way of securing the hanger in place is toprovide it with a hook-like portion l 4 which is hooked over the bead l5of the body portion 2 of the casing of the transformer and is clamped inplace between the cover 3 and the body portion 2 thus securelypositioning the hanger and the lectromagnet. The electromagnet has onelead l6 which extends to one side of a thermally responsive deviceindicated generally by the reference character IT. The other side of thethermally responsive device is connected by means of a lead l8 with oneside of a clip type or cartridge type fuse Ill. The other side of thefuse i9 is connected to a bracket secured to the line terminal 2| of thesecondary of the transformer. The other lead 22 from the electromagnetis secured to the neutral terminal 23 of the secondary. The leads l6 andI8 and 22 are bound together by suitable clips 24. They are relativelystiff and serve to hold the thermally responsive member in any adjustedposition below the level 5 of the oil within the body portion 2 of thecasing of the transformer.

The thermally responsive member ll may comprise a U-shaped Bakelitemember 25 which has one arm of a U-shaped member 26 formed of conductingmaterial secured to one of the arms of the member 25. The upper ends ofthe arm of the member 25 overlap and are soldered together aslindicate'd'at 2l'zby a'lowamelting point solder such as rosemetal 75 C. solder.The member 25 is made of spring metal and the arms of the member 25 tendto spring apart and when the temperature of the oil arrives at apredetermined point, it will melt the solder 21 and allow the free armof the membersZEztoispr'ingroutwardly to the dotted line position'shownin Figure 1 and engage the terminal 28 to which the lead I8 is attached,and thus closeithe circuitcof'the electromagnet. This causes alternatingcurrent to be supplied from the winding of the tranS- former to theelectromagnet and causes the armature. l-Moproduceamultitude of. :blowsagainst the'rhead ll *of the 'core ID, the impact fleeing transmitted-tothe-cover '3"WhiCh'aCtS. as a sounding rboard :and gives .-adistinctlyaudible indication of theoverload condition. :.Not-.on1y-wi1la linemanwho may or maynot'be looking for this indication be apprised of.the-overloadicondition of thetransformencbut it-has been found thatcustomers or other ,persons :in the vicinity -.will also be .apprised ofthis condition. :The customers =r persons in the vicinity will, in-turn, notify the power company and suitable steps will be taken to.remedy the overload acondition without delay *thus avoiding a longinterruption to service.

The fuse. l9. not onlyacts as a protectingmeans to -protectthe1transformer:inthe-event of: failure of the-electromagnetbutalso maybe used as -a disconnectingymeans if=so desired.

In the form of the invention showniin Figure 1, after overloadhasoccurred,.,theoverload audible indication -.is continuously given until-suitable steps have-been taken to correctuthe condition. However, itmay be desired to 'useaother-means whichwill give an audibleindicationonly :during the overload condition. -Any-.suitable'-means may beemployed forthis purpose. For instanca-a thermostatically responsivebellows F29, sec :Figures3, imayebe used. This ibellows -may=be made of-metal =.-and may carrythemovable contacted designed =to engage thestationary :contact -3I when an'overload occurs, the bellows and thecontact 5! being suitabl-y supported .on a .U- shaped insulating member:32. If desired abimetal thermostatic member, indicated: by thereference character 33- in'FigureA may: be employed and may..-carry:themovable: contact 34 adapted to engagethe stationary contact :35 uponoverload conditions.

Referringto:Figure.-2,-itiwillzbe seen that the transformer 'has "beenindicated-generallyby the reference character 4 and is provided Witha.primary 35 and a'secondary 31. :I'hethermallyresponsivamember isindicated; in Figure :2 generally-by'the reference character '11, thefuse at |.9,- and ethe electromagnet generally at '8.

It will be seen thata' novel formof overload indicating means,:particularly suitable 'for distribution transformers, has been providedby this invention which will give 5a distinct audibleindication of theoverload condition and .which not only will apprise a lineman :when: in*the vicinity of the transformerwhether heris lookingxfor the indication'or not, but Will also apprise the customers or-ianyiperson in thevicinityiof the overload condition whogit 'is-expected, will-in turnnotify the power "company.

.It'will be "seen that zthe device "can be very cheaply made primarilyfrom standardstock material sand :also :can "be rmosteasily installed intion of a transformer provided ivitii g easing containing oil, and anoverload indicator arrangedito produce an audible sound and com, isingan electromagnet having an armature-arranged to strike blows when theelectromagnet is energized 1 by aiternating current andzinolndingimeans'for transmitting the: impact ofesaidblows to the casingof thetransformer, a portion at least-of said casingibeing.arrangedtto act-asasounding board, andthermally. responsive means-'immersedin-said oil andarranged'toelectrically connect saidaelectromagnetto'the .tr.ansformerwhen the oil rreaches a-prcdetermined temperature.

'2. The-combination of a transformerprovided with-a scasingncontaim'ng,oil I and having a body portion and a cover, and an overload indicatorarranged toproduce Ql'lr'dlldlblBSOllIldzfiHd comprising anelectromagnet and an:armature,'said electromagnet comprising aimainyportion and arr armature: arranged .tostrike-said main; portion amultitude ofblows when; said electromagnetis energized withalternating-:current, a hanger having aportion clampedbetween the" coverand body portion of :said casing andarranged to hold-the main portion.of theeelectromagnet against said cover,-andthermallyresponsive meansimmersed in the oil 'and :arranged to electrically" connect saidelectromagnet with the transformer when theoil reachesa predeterminedtemperature.

- 3. An audible indicator for an encased transformer tcomprising-ahanger arranged to besecured tozthe casingofsa-id transformer;arr-electromagnet carried -.by.-said hanger and having a body portionarranged to be held by. said hanger in 1 contact =With the a casing ofsaid transformer and having an armature:arrangedtmstrike-the bodyportion .of said electromagnet a-.mu1titude of blows whensaidelectromagnet.is energized with alternating current to thereby' cause aportion at=-leastof said casingitoa-ctas asounding board, said armaturebeing resiliently supported and being arranged toresonate with. thealternating current, and means including thermallyi'responsive meansarranged :to electrically connect said electromagnet to the. transformerwhen said thermally responsive means is heatedto a predetermined degree.

EDWIN SIMEO'N BUNDY.

"REFERENCES CITED .The'following"references'areof record in the file .ofthis patent:

" UNITED STATES PATENTS Number Name Date 1,443,786 aDolph Jan. 30, 19231,635;348 i-Samper July12, 192'7 =,1,'71'7 ;216 Isaac June 11, 19291,718,216 .Burnham .June 25, 1929 975,459 Holslag Oct. 2, 1934 2,298,126Hodnette Oct," 6, 1942 2,3195% Treanor May 18, 1943 223251470 .BonannoJuly 2'7, 1943 2,327,684 Warrick Aug. 24,1943

